A catheter-type semiconductor detector and associated electric system have been developed, in co-operation with Mitsubisei Electric Corp., for the diagnosis of malignant tumors. We illustrated the mechanism of a new catheter-type semiconductor detector. The performance test of the new catheter-type detector measures 2.5mm in diameter and 150cm in length was made. This detector is small enough to insert in the stomach or esophageal fiberscope. The image of ^<32>P was also abtained by the semiconductor detector connected with a scintiscanner in our laboratory. With this combination we are able to demonstrate with clarity the distribution of ^<32>P in cancerous tissue.
The radiation-induced ultraviolet absorption in transparent plastic ([-CH_2・C (CH_3) COOR-]_n, Acrylite, Mitsubishi) has been investigated in detail and found to be a convenient, inexpensive and accurate method of measuring radiation doses between 5×10^4 and 1.8×10^6 rads In Acrylite the change in absorbance at 330mμ is a linear function of the dose up to about 1.8 megarads. Various factors that may influence the reproducibility of results have been investigated. The calibration curves, relating to the change in absorbance to the dose in rads, measured by the Fricke ferrous sulfate dosimeter, is given. An example, the measurment of gamma-ray-intensity distribution of our ^<60>Co cylindrical source, is given as the application of this technique to dosimetry.